876 PROFESSOR W. C. M‘INTOSH AND MR E. E. PRINCE ON 
vein passing upon the right, and in some a distinct bulging of the yolk-sac occurs in 
front of the globule. Moreover, during the extremely cold weather of the period, 
the globule was often thrust outward at this part. The head of the embryo 
presents a remarkably truncate appearance, the snout, indeed, projecting less than the 
large eyes, when viewed from the dorsum (as in the figure just mentioned). A decided 
difference exists, therefore, in this respect, when compared with the young salmon, in 
which the long yolk-sac trends downward and backward, whereas in this form the 
yolk-sac is globular, and is directed downward and forward. 
This being, so far as known, the largest British marine Teleostean larva yet 
described, its comparison with that of the salmon, the largest fresh-water form, is 
naturally suggested. Many points of contrast are at once presented; thus the difference 
in coloration is marked, for while both have pigment in the eyes, the yolk in Anarrhichas 
is straw-coloured and inconspicuous, whereas in the salmon it is rendered conspicuous by 
the deep reddish-orange colour of the oleaginous globules. The latter become grouped, 
again, in masses in the upper region of the yolk-sac; whereas in Anarrhichas the 
single, large, somewhat lenticular globule maintains a constant position in front. The 
general pinkish tint of the newly-hatched salmon, further, is more pronounced. The 
external features of the wolf-fish also present less differentiation, for the marginal fin is 
simple and continuous, the tail is lanceolate, and the pectoral fins at this stage are much 
smaller. The head, moreover, is very different, for when viewed from the dorsum 
(Pl. XX. fig. 5), the large eyes, as already noted, project even further than the snout; 
while in the salmon the snout protrudes considerably beyond the eyes. 
In a newly-hatched example about a week later (1st February) the tail is somewhat 
bluntly lanceolate, the ventral lobe being more distinct than the dorsal (Pl. XX. fig. 1), 
and the notochord passes in a straight line backward to terminate in a point. A slight 
wrinkle of the margin of the delicate caudal membrane occasionally marks this termina- 
tion. The notochord here is finely cellular, the size of the cells increasing anteriorly. 
The neurochord presents a marked diminution just above the margin of the vascular loop 
beneath the notochord. The membranous tail-fin has fine striae (embryonic rays, 
produced by delicate fibres), and is cellulo-granular. The aorta, in coursing back- 
ward, gives off a twig inferiorly, which diverges from the ventral surface of the noto- 
chord, and then ends in a slender vessel passing almost to the tip of the chorda, and 
returns as a recurrent vein. The ventral twig of the aorta splits into two loops, which 
ramify over a limited area (see Pl. XX. fig. 1), and then joins the caudal vein by a single 
trunk. This condition diverges from that in the salmon at the same stage, but a com- 
parison between the two forms may be conveniently reserved till a later period. The 
circulation in the caudal region attains but a slight development in the wolf-fish at this 
stage, whereas the vitelline vessels are as fully developed as in more advanced 
larvee. 
Vitelline Circulation at the Period of Hatching.—We have already mentioned that 
on emerging a large vitelline vein passes on the right side of the larval trunk, collecting 
